perf: checkpoint

crates/television-previewers/src/previewers.rs

@@ -176,24 +176,10 @@ impl Previewer {
             // if we got a preview, cache it
             if let Some(preview) = preview {
                 self.cache.lock().insert(entry.name.clone(), &preview);
-                Some(preview)
-            } else {
-                None
+                return Some(preview);
             }
-        } else {
-            debug!("Not past debounce duration");
-            // partial preview
-            let preview = match &entry.preview_type {
-                PreviewType::Basic => Some(self.basic.preview(entry)),
-                PreviewType::EnvVar => Some(self.env_var.preview(entry)),
-                PreviewType::Files => self.file.preview(entry),
-                PreviewType::Command(cmd) => {
-                    self.command.partial_preview(entry, cmd)
-                }
-                PreviewType::None => Some(Arc::new(Preview::default())),
-            };
-            Some(preview)
         }
+        None
     }
 
     pub fn set_config(&mut self, config: PreviewerConfig) {

crates/television-previewers/src/previewers/basic.rs

@@ -23,7 +23,6 @@ impl BasicPreviewer {
             title: entry.name.clone(),
             content: PreviewContent::PlainTextWrapped(entry.name.clone()),
             icon: entry.icon,
-            ..Default::default()
         })
     }
 }

crates/television-previewers/src/previewers/env.rs

@@ -36,7 +36,6 @@ impl EnvVarPreviewer {
                 PreviewContent::Empty
             },
             icon: entry.icon,
-            ..Default::default()
         });
         self.cache.insert(entry.clone(), preview.clone());
         preview

crates/television-previewers/src/previewers/files.rs

@@ -1,4 +1,3 @@
-use color_eyre::Result;
 use parking_lot::Mutex;
 use rustc_hash::{FxBuildHasher, FxHashSet};
 use std::collections::HashSet;
@@ -9,6 +8,10 @@ use std::sync::{
     atomic::{AtomicU8, Ordering},
     Arc,
 };
+use television_utils::files::{read_into_lines_capped, ReadResult};
+use television_utils::strings::{
+    replace_non_printable, ReplaceNonPrintableConfig,
+};
 
 use syntect::{highlighting::Theme, parsing::SyntaxSet};
 use tracing::{debug, warn};
@@ -127,6 +130,10 @@ impl FilePreviewer {
     }
 }
 
+/// The size of the buffer used to read the file in bytes.
+/// This ends up being the max size of partial previews.
+const PARTIAL_BUFREAD_SIZE: usize = 16 * 1024;
+
 pub fn try_preview(
     entry: &entry::Entry,
     cache: &Arc<Mutex<PreviewCache>>,
@@ -137,29 +144,45 @@ pub fn try_preview(
 ) {
     debug!("Computing preview for {:?}", entry.name);
     let path = PathBuf::from(&entry.name);
-    // check file size
-    if get_file_size(&path).map_or(false, |s| s > MAX_FILE_SIZE) {
-        debug!("File too large: {:?}", entry.name);
-        let preview = meta::file_too_large(&entry.name);
-        cache.lock().insert(entry.name.clone(), &preview);
-    }
 
     if matches!(FileType::from(&path), FileType::Text) {
         debug!("File is text-based: {:?}", entry.name);
         match File::open(path) {
             Ok(file) => {
                 // compute the highlighted version in the background
-                let mut reader = BufReader::new(file);
-
-                reader.seek(std::io::SeekFrom::Start(0)).unwrap();
-                let preview = compute_highlighted_text_preview(
-                    entry,
-                    reader.lines().map_while(Result::ok).collect(),
-                    syntax_set,
-                    syntax_theme,
-                );
-                cache.lock().insert(entry.name.clone(), &preview);
-                in_flight_previews.lock().remove(&entry.name);
+                match read_into_lines_capped(file, PARTIAL_BUFREAD_SIZE) {
+                    ReadResult::Full(lines) => {
+                        let preview = compute_highlighted_text_preview(
+                            entry,
+                            &lines
+                                .iter()
+                                .map(|l| preprocess_line(l).0 + "\n")
+                                .collect::<Vec<_>>(),
+                            syntax_set,
+                            syntax_theme,
+                        );
+                        cache.lock().insert(entry.name.clone(), &preview);
+                        in_flight_previews.lock().remove(&entry.name);
+                    }
+                    ReadResult::Partial(p) => {
+                        let preview = compute_highlighted_text_preview(
+                            entry,
+                            &p.lines
+                                .iter()
+                                .map(|l| preprocess_line(l).0 + "\n")
+                                .collect::<Vec<_>>(),
+                            syntax_set,
+                            syntax_theme,
+                        );
+                        cache.lock().insert(entry.name.clone(), &preview);
+                        in_flight_previews.lock().remove(&entry.name);
+                    }
+                    ReadResult::Error(e) => {
+                        warn!("Error reading file: {:?}", e);
+                        let p = meta::not_supported(&entry.name);
+                        cache.lock().insert(entry.name.clone(), &p);
+                    }
+                }
             }
             Err(e) => {
                 warn!("Error opening file: {:?}", e);
@@ -177,7 +200,7 @@ pub fn try_preview(
 
 fn compute_highlighted_text_preview(
     entry: &entry::Entry,
-    lines: Vec<&str>,
+    lines: &[String],
     syntax_set: &SyntaxSet,
     syntax_theme: &Theme,
 ) -> Arc<Preview> {
@@ -185,12 +208,6 @@ fn compute_highlighted_text_preview(
         "Computing highlights in the background for {:?}",
         entry.name
     );
-    let lines: Vec<String> = lines
-        .iter()
-        // we need to add a newline here because sublime syntaxes expect one
-        // to be present at the end of each line
-        .map(|line| preprocess_line(&line).0 + "\n")
-        .collect();
 
     match syntax::compute_highlights_for_path(
         &PathBuf::from(&entry.name),

crates/television-screen/src/preview.rs

@@ -31,7 +31,6 @@ const FILL_CHAR_EMPTY: char = ' ';
 
 #[allow(clippy::needless_pass_by_value)]
 pub fn build_preview_paragraph<'a>(
-    //preview_block: Block<'_>,
     inner: Rect,
     preview_content: PreviewContent,
     target_line: Option<u16>,

crates/television-utils/src/files.rs

@@ -1,6 +1,8 @@
 use rustc_hash::FxHashSet;
 use std::fmt::Debug;
 use std::fs::File;
+use std::io::BufRead;
+use std::io::BufReader;
 use std::io::Read;
 use std::path::Path;
 use std::path::PathBuf;
@@ -14,6 +16,51 @@ use crate::strings::{
 };
 use crate::threads::default_num_threads;
 
+pub struct PartialReadResult {
+    pub lines: Vec<String>,
+    pub bytes_read: usize,
+}
+
+pub enum ReadResult {
+    Partial(PartialReadResult),
+    Full(Vec<String>),
+    Error(String),
+}
+
+pub fn read_into_lines_capped<R>(r: R, max_bytes: usize) -> ReadResult
+where
+    R: Read,
+{
+    let mut buf_reader = BufReader::new(r);
+    let mut line = String::new();
+    let mut lines = Vec::new();
+    let mut bytes_read = 0;
+
+    loop {
+        line.clear();
+        match buf_reader.read_line(&mut line) {
+            Ok(0) => break,
+            Ok(_) => {
+                if bytes_read > max_bytes {
+                    break;
+                }
+                lines.push(line.trim_end().to_string());
+                bytes_read += line.len();
+            }
+            Err(e) => {
+                warn!("Error reading file: {:?}", e);
+                return ReadResult::Error(format!("{e:?}"));
+            }
+        }
+    }
+
+    if bytes_read > max_bytes {
+        ReadResult::Partial(PartialReadResult { lines, bytes_read })
+    } else {
+        ReadResult::Full(lines)
+    }
+}
+
 lazy_static::lazy_static! {
     pub static ref DEFAULT_NUM_THREADS: usize = default_num_threads().into();
 }

crates/television-utils/src/strings.rs

@@ -224,7 +224,7 @@ pub fn replace_non_printable(
     input: &[u8],
     config: &ReplaceNonPrintableConfig,
 ) -> (String, Vec<i16>) {
-    let mut output = String::new();
+    let mut output = String::with_capacity(input.len());
     let mut offsets = Vec::new();
     let mut cumulative_offset: i16 = 0;
 

crates/television-utils/src/syntax.rs

@@ -8,7 +8,7 @@ use tracing::warn;
 
 pub fn compute_highlights_for_path(
     file_path: &Path,
-    lines: Vec<String>,
+    lines: &[String],
     syntax_set: &SyntaxSet,
     syntax_theme: &Theme,
 ) -> color_eyre::Result<Vec<Vec<(Style, String)>>> {